This invention relates generally to gas turbine engines, and more particularly, to methods and apparatus for assembling gas turbine engine compressors.
At least some known gas turbine engines include, in serial flow arrangement, a compressor, a combustor, a high pressure turbine, and a low pressure turbine. The compressor, combustor and high pressure turbine are sometimes collectively referred to as the core engine. Compressed air is channeled from the compressor to the combustor where it is mixed with fuel and ignited. The combustion gasses are channeled to the turbines which extract energy from the combustion gasses to power the compressors and to produce useful work to propel an aircraft in flight or to power a load, such as an electrical generator.
Known compressors include a rotor assembly and a stator assembly. Known rotor assemblies include a plurality of rows of circumferentially-spaced rotor blades that extend radially outward from a shaft or disk. Known stator assemblies may include a plurality of stator vanes which extend circumferentially between adjacent rows of rotor blades to form a nozzle for directing air passing therethrough towards downstream rotor blades. More specifically, known stator vanes extend radially inward from a compressor casing between adjacent rows of rotor blades.
In at least some compressors, each stator vane is unitarily formed with an airfoil and platform that are mounted through an integrally-formed dovetail to the compressor casing. To facilitate assembly of the stator vanes to the casing, a small amount of clearance is permitted between a casing dovetail or vane rail and the vane platform. However, the clearance enables a small degree of relative motion between the vane platform and the casing vane rail. Over time, continued movement between the stator vanes and the casing rail may cause vane platform and/or casing wear. Such relative movement of the stator vanes may be enhanced by vibrations generated during engine operation.
To facilitate reducing wear between the casing and vane platform, at least some stator assemblies are coated with wear coatings or lubricants. Other known compressors use casing rail liners, and/or vane springs to facilitate reducing such wear. However, known wear coatings may not be useful in some single vane applications, and known vane springs may not be suitable for use with vanes that include air bleed holes. Moreover, known rail liners are only useful in a limited number of engine designs.